Boom Control

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Redlion

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There has been at least 6 high profile deaths in the last year due to booms swinging out of control on ocean passages. It strikes me that it cannot be beyond the skill of engineers to develop an apparatus that sits under the boom and prevents it from moving rapidly from one side to another.
I don't understand why manufacturers do not even offer a boom brake as an option on a new yacht or even make provision for the fixings so it can be installed neatly without cluttering the side decks.
 
Solo's I think use a piece of shock cord attached to the bow and to each side of the boom so something like that maybe scaled up, and I'm sure many of the more traditional boats rigged up a 'preventer' to stop an uncontrolled gybe.
 
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It is beginning to look as if boom control is becoming a significant factor in racing and other fatalities. I admit that it is not my field, but if this is what the statistics show, then the designers and race people should get together and make sure that unnecessary deaths don’t happen from this cause, in the way that lifejackets and other things are mandated. A significant advantage would be that good design and practice would then trickle down into the cruising market.
 
Redlion said:
There has been at least 6 high profile deaths in the last year due to booms swinging out of control on ocean passages. It strikes me that it cannot be beyond the skill of engineers to develop an apparatus that sits under the boom and prevents it from moving rapidly from one side to another.
I don't understand why manufacturers do not even offer a boom brake as an option on a new yacht or even make provision for the fixings so it can be installed neatly without cluttering the side decks.
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There are lots of bits of kit that work as boom brakes, all pretty rubbish in the opinion of this retired engineer. Nothing wrong with a long preventer.

The two deaths on the Hobart Race were on racing boats and in my extremely limited experience of crewing on boats skippered by 'out and out racers' they either don't use preventors or think that somebody can hold the boom at the correct angle. In the manner shown below.
 
Redlion said:
There has been at least 6 high profile deaths in the last year due to booms swinging out of control on ocean passages. It strikes me that it cannot be beyond the skill of engineers to develop an apparatus that sits under the boom and prevents it from moving rapidly from one side to another.
I don't understand why manufacturers do not even offer a boom brake as an option on a new yacht or even make provision for the fixings so it can be installed neatly without cluttering the side decks.
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Welcome to the forum. There are several such devices on the market as well alternate ways of using preventer ropes to control booms. Frequently (and recently) covered in yachting magazines. However most of the cases such as the recent ones in Australia are on race boats and boom control devices are not necessarily compatible with racing boat handling.
 
Egret said:
Solo's I think use a piece of shock cord attached to the bow and to each side of the boom so something like that maybe scaled up, and I'm sure many of the more traditional boats rigged up a 'preventer' to stop an uncontrolled gybe.
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Sounds good. It's not uncommon to see people in marinas being escorted with bandaged heads .

I wonder if a ratchet block could be permanently rigged between the boom and mainsheet tackle. At least slowing the boom a bit. I believe you can buy ratchet blocks with on/off switches. Perhaps there are some where the tension can be adjusted ? The downside being too much slack in the mainsheet ?

Just found this. Mainsail shock absorber Sail-fuse® | Nodusfactory-Sail
 
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I've always wondered whether a car shock-absorber (or two) couldn't be used (if corrosion could be overcome) - something like koni's frequency sensitive damping would be just the ticket, damping harder when you push faster
 
rogerthebodger said:
https://flic.kr/p/2hB477p

Tos is te boom control device I designed and fabricated from a large stainless-steel shackle and a stainless-steel ring stick welded together and a line around the device back to the chain plate on one side and through a pully on the other chain plate then back to the cockpit for tension adjustment
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I used a 'Petzl' figure of eight climbing decender. Worked a treat and was cheap.
 
I usually rig a preventer when running and sometimes reaching offshore. I attach it where the mainsheet attaches about 3/4 along the boom using a 2:1 purchase and snatch blocks to the toerail and boom. It does two useful things - stops the boom slamming in rolly seas and stops the boom crashing across in the event of a gybe which has happened a few times. Because the preventer rope is kept tight and the mainsail is relatively small and often reefed it works. I run the preventer to the toe rail at two points to spread the load.

There is much debate on the forum about preventers and boom brakes. I would like to "upgrade" to a boom brake because I can see the benefit in stopping or delaying the boom slamming across but avoiding the full load of holding the boom to windward after a gybe. But I still want the benefit of the preventer in stopping the slamming in rough seas or lighter winds. Not sure if a boom brake can also double as a preventer (and stop the slamming).

I like #6 device. Experimentation and practice.
 
It's normal practise on Dragonflys to rig a preventer when cruising, enabling twist control when the boom is right out as a side benefit, as we don't have a kicking strap of any kind. It's never used when racing though. Fortunately you'd have to be super tall to head butt the boom, the cockpit floor is low, and the boom is relatively high. That must surely be primary safety? If you have a deck sweeping boom, or a higher floor, clearly it's a bigger danger.
 
Chiara’s slave said:
…If you have a deck sweeping boom, or a higher floor, clearly it's a bigger danger.
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Very true. Trouble is with most boats is that you’re often below boom level in the cockpit but very much in the line of fire when going forward on the side decks. That’s the trouble with preventers - you have to go forward to set them up. I like Roger’s setup because it’s permanently there and ‘switching it on’ just involves tensioning a line led back to cockpit.
 
Supertramp said:
... attach it where the mainsheet attaches about 3/4 along the boom ...
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Your boom might be at a higher risk of snapping in an accidental gybe when the main backs. The load distribution is more evenly spread along the boom if the gybe preventer is attached to the end of the boom. I read this fact and supporting calculations in a recent discussion on exactly this point, where to attach a gybe preventer on www.morganscloud.com which is a subscription service.
 
fredrussell said:
Very true. Trouble is with most boats is that you’re often below boom level in the cockpit but very much in the line of fire when going forward on the side decks. That’s the trouble with preventers - you have to go forward to set them up. I like Roger’s setup because it’s permanently there and ‘switching it on’ just involves tensioning a line led back to cockpit.
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Gybe limiters are friction dependent and need set up for the wind speed. Hence one wrap or two wraps may have too much friction or insufficient friction. They are not fit and forget, the friction needs to be set for the wind speed.
 
Chiara’s slave said:
... the cockpit floor is low, and the boom is relatively high. That must surely be primary safety? If you have a deck sweeping boom, or a higher floor, clearly it's a bigger danger.
Click to expand...

On one of the RTW races, Clipper IIRC, the crew was killed when struck by the sweeping mainsheet. On a sail training yacht I worked on, a similar thing happened except it was a rather nasty friction burn, but they still got knocked down and entangled under the mainsheet. The boom is not the only direct hazard in an accidental gybe. Also the sudden change and reverse of heal angle, loss of balance, flying objects et cetera.
 
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